Numbers k such that 4 and 5 occur juxtaposed in the base-10 representation of k but not of k+1.

Terms

a(0) =45a(1) =54a(2) =145a(3) =154a(4) =245a(5) =254a(6) =345a(7) =354a(8) =445a(9) =459a(10) =549a(11) =554a(12) =645a(13) =654a(14) =745a(15) =754a(16) =845a(17) =854a(18) =945a(19) =954a(20) =1045a(21) =1054a(22) =1145a(23) =1154a(24) =1245a(25) =1254a(26) =1345a(27) =1354a(28) =1445a(29) =1459